STRUCTURAL SYSTEM AND HYDROCARBON DISTRIBUTION IN THE BOHAI GULF BASIN

The Bohai Gulf basin is an important hydrocarbon base of China.In the basin many types of structural systems such as en-echelon and brush structural systems are developed and show a complex spatial distribution.The hydrocarbon accumulation and occurrence in the basin are controlled by different orders of the structural systems.Five hydrocarbon provinces,namely,the Jiyang and Huanghua brush hydrocarbon provinces,Lower Liaohe-Bohai arcuate hydrocarbon province and Jizhong and Dongpu en-echelon hydrocarbon provinces,may be distinguished in the Bohai Gulf basin.There are appreciable differences in hydrocarbon amounts and distribution characteristics between the five hydrocarbon provinces.Among these hydrocarbon provinces,the Jiyang brush hydrocarbon province contains the most abundant hydrocarbon resources and the Dongpu en-echelon hydrocarbon province has the smallest reserves.The Paleogene was the most important stage of structural evolution in the Bohai Gulf basin and is most closely related to hydrocarbon generation and accumulation formation.In the stage,the development of source rocks reached the culmination and many types of petroleum accumulation and several source-reservoir-seal combinations occurred.The Neogene witnessed the development of secondary petroleum accumulations dominated by drape anticline accumulations and good regional cap rocks in the basin.The complicated structural evolution of the Bohai Gulf basin brought about the formation of multiple source-reservoir-seal combinations.So the basin possesses basic geological conditions for the formation of large hydrocarbon regions.